"Our data suggest that zebra mussels promote Microcystis at low to medium phosphorous levels not at very low or very high phosphorous levels," he said. "However, we're still not sure why this happens."

Zebra mussels have been causing problems in the Great Lakes since the late 1980s. For example, in Lake Erie, Sarnelle said, increased incidence of blue-green algae blooms have been reported since the establishment of zebra mussels.

"Similarly, data from the Bay of Quinte in Lake Ontario show a dramatic increase in the biomass of Microcystis after zebra mussel establishment," he said. "In addition, toxic algal blooms in Saginaw Bay and Lake Erie are disturbing because they come after many years of expensive reductions in nutrient loading to improve water quality."

Zebra mussels, which are native to the Caspian Sea region of Asia, were first discovered in Lake St. Clair in 1988. It's believed they were transported to the Great Lakes via ballast water from a transoceanic vessel.

Since then, they have spread to all of the Great Lakes, as well as many other U.S. and Canadian inland lakes and rivers.

Sarnelle's co-authors on the paper are Alan Wilson of the Georgia Institute of Technology, and David Raikow and Stephen Hamilton of the MSU Department of Zoology and Kellogg Biological Station.

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Contact: Gisgie Dvila Gendreau
gendrea3@msu.edu
517-355-2281
Michigan State University
10-Mar-2004